This invention relates to novel plastic compositions having enhanced environmental degradability.
The advent of plastics has given rise to improved methods of packaging goods. For example, polyethylene and polypropylene plastic films, bags, bottles, styrofoam cups and blister packages have the advantages of being chemically resistant, relatively unbreakable, light in weight and translucent or transparent. The increasing use of plastics in packaging applications has created a serious waste disposal problem. Burning of these plastic materials is unsatisfactory since it adds to air pollution problems.
Unlike some other packaging materials, such as paper and cardboard, plastics are not readily destroyed by the elements of nature. Thus, burying them is not an effective means of disposal, and can be expensive.
Plastics are biologically recent developments, and hence are not easily degradable by micro-organisms which attack most other forms of organic matter and return them to the biological life cycle. It has been estimated that it may take millions of years for organisms to evolve which are capable of performing this function. In the meantime, plastic containers and packaging films are beginning to litter the countryside after being discarded by careless individuals.
One approach to the alleviation of the problem of plastics waste and litter would involve the development of novel polymeric compositions which undergo accelerated degradation under environmental conditions. This general approach has been described in the prior art. For example, reference is made to British Pat. Specification No. 1,128,793, which describes ethylenecarbon monoxide copolymers which undergo rapid deterioration when subjected to sunlight.
The present invention resembles the prior art in that the degradability of polymeric materials is altered by the introduction of suitable degradation-sensitizing groups, but differs in that these groups are introduced via chemical modification of a previously synthesized polymeric material, rather than during the polymerization process.